Hydraulic jack



March 13, 1962 A. E. suNDlN 3,024,920

HYDRAULIC JACK Filed May 27, 1958 3 Sheets-Sheet 1 2 Hl'llmwwu IN VEN TOR. @um dA/M March 13, 1962 A. E. sUNDlN HYDRAULIC JACK 5 Sheets-Sheet 2 Filed May 2'?, 1958 INVENTOR. l

March 13, 1962 A. E. sUNDlN HYDRAULIC JACK 3 Sheets-Sheet 5 Filed May 27, 1958 United States Patent Giiice 3,024,920 Patented Mar. 13, 1962 3,024,920 HYDRAULIC JACK Anders Erik Sundin, Hudiksvall, Sweden, assignor to Hydrauliska Industri Aktiebolaget, Hudiksvall, Sweden,

a corporation of Sweden Filed May 27, 1958, Ser. No. 738,187 Claims priority, application Sweden May 28, 1957 2 Claims. (Cl. 212-35) The present invention relates to a hydraulic jack which is especially adapted to be arranged ou a lorry or other vehicle and which is provided with a lever beam swingable in vertical and horizontal directions relative to the body of the hydraulic jack, the movement in vertical direction partially caused by means of an hydraulic device comprising a pressure cylinder and a pressure piston, said pressure piston being at its upper end hinged to the lever beam, the latter being provided with a rocker arm, operated by a pressure cylinder having a pressure piston, said rocker arm being hinged to the part of said lever beam situated close to the body of the hydraulic jack, said rocker arm thereby being capable of moving a loading tool not only in vertical and horizontal directions but also in the direction to and from said body.

The main feature of the invention is in the construction of a joint between the rocker arm and lever beam and that the piston rod of the pressure piston arranged on the lever beam is hinged to the rocker arm near its joint in such a way that the lever beam at said joint forms a downwardly directed knee when said piston rod is in its pushed-out position, the rocker arm by means of its dead weight capable of being folded onto the other part of the lever beam when the latter is in its uppermost or almost uppermost position, transport with the vehicle thereby being facilitated.

The invention makes it possible to execute the folding action by means of the control valve of the hydraulic jack. -It is thus not necessary to climb onto the platform body of the lorry for the folding of the lever beam, but this operation can be executed from the ground where the lorry stands.

The invention will now be elucidated with reference had to the accompanying drawings. In the drawings:

FIG. 1 is a side elevation of an hydraulic jack according to the present invention having its lever beam directed rearwards,

FIG. 2 is a similar side elevation of the upper part of the hydraulic jack showing the lever beam swung upwards,

FIG. 3 is a partly broken rear View of the jack showing the lever beam folded, and

FIG. 4 shows on an enlarged scale a partly cut section on the line =IV---IV in FIG. l of the joint at the center of the lever beam.

On the frame of the chassis of a lorry, close behind its driving compartment 1, there is arranged a boxformed rail 2 which forms a container for the pressure medium, preferably oil, which hydraulically actuates the hydraulic jack. A pressure cylinder 3, serving as a vertical column or a body, has its lower end arranged at the rail 2, and at the upper end of the cylinder 3 there is arranged a device 4 for turning the lever or tilt beam 5 of the hydraulic jack in a horizontal plane. Said device 4 comprises inter alia two horizontal pressure cylinders 6 having pistons movable in them and a rack-gear arranged between said movable pistons. 'I'he rack-gear cooperates with a gear wheel journalled on the vertical pressure cylinder 3. The gear wheel is arranged at the lower end of a socket 7 which is rotatably carried on the upper end of the pressure cylinder 3. The socket 7 is provided with a box-formed guiding portion 8 which from above is passed through by a draw rod 9 which at its lower end has a curvature 10 adapted to cooperate with a laterally disposed stopper 11 in the guiding portion 8. The rod 9 is at its upper end hinged to the shorter arm 13 of the tilt or lever beam 5 by means of a bolt 12. A pressure piston 14 is movably arranged in the vertical pressure cylinder 3, and this piston 14 is at its upper end hinged to the tilt or lever beam 5 at the fulcrum portion thereof by means of a bolt 1'5 in such a Way that the lever beam 5 forms a two-armed lever.

The tilt or lever beam 5 comprises a part or arm 16 longer than said shorter arm 13, situated close to the body of the hydraulic jack, and a rocker arm or load beam 17 hinged to the longer arm 16. The load beam 17 carries at its outer end a loading tool which, according to FIG. 2, comprises a chain 18 with a load hook 19. The joint between the load beam 17 and the portion 16 of the lever arm comprises two coaxial pivots 20 spaced laterally from each other. The axial line of the pivots 2t) is almost in level with the upper plane of the lever beam 5. A pressure cylinder 22 having a pressure piston is swingably carried with one end around a bolt 21 in the longer arm 16 of the lever beam 5. The piston rod 23 of the pressure piston in the pressure cylinder 22 is hinged at the load beam 17 by means of a bolt 24 at a place situated in the vicinity of the pivots 20 but underneath the latter. The joint is performed in such a way that the load beam 17 forms with the longer arm 16 a downwardly directed knee (FIG. 2) when the piston rod 23 is in its pushed-out position. In this position, the piston rod 23 extends through the space between the pivots 20` (FIG. 4).

The means for controlling the feeding of pressure medium to the different pressure cylinders are shown only diagrammatically in the drawings. The hydraulic pump (not shown) is preferably coupled to the transmission machinery of the lorry. The pressure side of the pump communicates through a conduit 25 with a control valve 26. The valve body of the latter can be adjusted to different control positions by means of operating handles 127, 28 on both sides of the lorry (only one of them shown in FIG. 3). The valve 26 communicates by means of a conduit 29 with the outer end of the right hand pressure cylinder 6 (FIG. 3) and by means of a conduit 30 with the outer end of the left hand pressure cylinder 6. The valve 26 further communicates by means of a conduit 31 with the vertical pressure cylinder 3. Finally, the valve 26 communicates by means of a iiexible conduit 32 with the pressure cylinder 22 on the lever beam 5.

When the lever beam 5 is in the position shown in FIG. 1 and after loading or unloading work having been finished, it is desired to fold the lever beam so that the latter does not require too much space when the lorry is driven on a public road. The control valve 26 is then adjusted in such a way that pressure oil is pressed through the conduit 32 and into the pressure cylinder 22. The piston rod 23 then swings the load beam 17 upwards in such a Way that the lever beam 5 forms a downwardly directed knee at its central joint (pivots Zit). The valve 26 is thereupon adjusted in such a way that pressure oil is pressed through the conduit "31 and into the pressure cylinder 3, the pressure piston 14 thereby being pressed upwardly while bringing along the lever beam 5 together with the draw rod 9. When the curvature 10 of `the latter abuts against the stopper 11, the lever beam 5 is raised. When the raising of the lever beam 5 has continued so far that the vertical line 33 from the center of gravity of the load beam 17, in FIG. 2 designated with 34, passes on the left hand side of the center line of the pivots 20, the feeding of pressure medium to the pressure cylinder 3 is interrupted. The control valve 26 is then adjusted in such a way that pressure medium can flow out of the pressure cylinder 212 and through the conduit 32 and return to the container 2. The load beam 17 is thereby folded rearwardly (to the left according to FIG. 2) by its own dead weight and comes to rest upon the longer arm 16 ofthe lever beam 5. The control valve 26 is finally adjusted to a position in which the pressure medium is permitted to ow out of the pressure cylinder 3, through the conduit 31 and back to the container 2. The pressure piston 14 is thereby lowered, and in the lowermost position the lever beam 5 is in the position shown in FIG. 3.

When the lever beam 5 is to be returned to operating position (FIG. l), the operation described here above is performed but, of course, in the reversed direction.

The shown and described embodiment is to be regarded only as an example, and the different portions of the hydraulic jack could be constructively changed in many ways within the scope of ythe invention. When two pressure cylinders 22 are used, one of these cylinders could be arranged on each side of the part 16 of the lever beam 5. In such a case the pivots 20 could be replaced by a through-shaft. The invention could also be executed at loading devices having their lever beam 5 hinged to the vertical pressure cylinder 3 by means of their shorter end, the vertical cylinder 3 then being turnably carried on the body of the apparatus.

What I claim is:

1. A folding crane boom for lorry loaders comprising a tilt beam having short and long arms Iand a fulcrum portion therebetween; substantially vertical relatively reciprocatory means pivotally secured to the short arm and fulcrum portion respectively 'for tilting the beam in a vertical plane to raise and lower the long arm; a knee-shaped hinge-joint on the outer end of the long arm; a load beam having the inner -end thereof secured on the hinge joint for moving in said plane and provided with loading means at the outer end, said joint having a pintle suiciently offset upwardly from the long arm and load beam, when the long arm and load beam are in outstretched horizontal position, to permit the load beam to fold back upon and rest on the long arm; an hydraulic cylinder and piston provided with a rod means and mounted on the long arm near the lower portion thereof and extending in the general direction of the long arm, the outer end of the rod means being connected to said load beam near said inner end thereof in a position sufficiently remote from the pintle to turn the load beam about lthe pintle with respect to the tilt beam as the rod reciprocates the pintle, rod means, and location of the connection of the latter to the load beam being so related that action of the cylinder may partially turn the load beam back toward the long arm; the pintle and rod means being shaped to clear each other while the load arm is being folded back in the long arm, the long yarm of the tilt beam being vertically movable about the fulcrum portion to sufficient height to bring the center of gravity of the load beam, in elevated position, inner of the pintle so that the load beam may, by gravity, fold back upon the tilt beam.

2. In a folding boom for a loader for lorries, inner and outer beam pieces having a knee-joint joining same end- -to-end; pivot means for pivotally mounting the inner piece to permit movement of the joint in a vertical plane substantially about a point; means for tilting the inner piece to oscillate the pieces about said point to selectively move the center of gravity of the outer piece inwardly; said' joint having a forked portion on each of the beam pieces, the branches of the forked portions each being provided with a pintle bolt lying substantially in the plane of the top of the pieces when both pieces are in outstretched position, so that the outer piece may fold back and rest upon the inner piece; an hydraulic cylinder and piston rod therefor mounted on the inner beam piece and extending along near the bottom thereof, the rod being hinged to the lower portion of the outer piece when the pieces are outstretched sutiiciently remote from the bolts for the rod to turn the outer piece in the direction to fold the latter back on the inner piece and move the center of gravity of the outer piece inwardly, the limit of upper movement of the inner piece and joint about said point being sufficiently high, and the limit of turning of the outer piece in said direction being sutiicient, to enable the center of gravity of the outer piece to be on a vertical line between said point and joint, said cylinder being hingedly mounted on the inner piece and the rod lying in space between the bolts so that when the inner piece is tilted upwardly suiciently and the piston rod expelled, the outer piece will be turned about the bolts and the rod pass between the bolts to permit the center of gravity of the outer piece to pass inner of the bolts and the outer piece may, by gravity, fold over on the inner piece.

References Cited in the file of this patent UNITED STATES PATENTS 2,598,517 Drott May 27, 1952 2,828,867- Frisk Apr. l, 1958 2,895,622 Sundin July 2l, 1959 FOREIGN PATENTS 1,140,892 France Mar. ll, 1957 

